How old is 400 gram baby?

Question
I know each guinea pig is different but we purchased 2 male guinea pigs 2 weeks ago and were told they were 8 weeks old. I have since seen GPs in pet shops that I am told are also 8 weeks old but these are considerably larger than mine. (mine would now be 10 weeks old). Mine now both weigh 400 grams (approximately 14oz). Do you think we are mistaken and our guinea pigs are younger than this?  

Answer
Hello Hilary,

Every pig is different and your's may well be 10 weeks old. Based on weight charts from my past litters, you may have bought 4 week olds, so they would be about 6 weeks now. However, I did have a slow growing runt from a difficult delievery who was that size at that age. I'm guessing these are pet store pigs? If so, they may very well be 10 weeks old. Too often they come from not so good places and don't grow quite as well at first because of it. I know this isn't very helpful and I'm sorry but piggies really do have a fairly wide "normal" weight range when they are little. Alot depends on how they are cared for. With plenty of food and love, even if they are a bit small, they should grow well. I wish I could be of more help.

-kkat
www.geocities.com/abyssinianguineapigs